Recombinant human erythropoietin (rhEPO) was given in 2 phases to 17 patients with rheumatoid arthritis (RA) and anemia. In the 8-week randomized study, 4/13 patients who received rhEPO had at least a 6-unit increase in hematocrit. 11 who completed the subsequent 24-week open-label study reached a normal hematocrit. No adverse effects were seen. rhEPO is an effective and potent treatment of anemia caused by RA.